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Mail Archives: geda-user/2016/01/09/14:27:20

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Date: Sat, 9 Jan 2016 10:27:06 -0900
Message-ID: <CAC4O8c9=RxTOOMV6neKbvF1arEMwNpDDP+HybYXzOv-RpWR=qw@mail.gmail.com>
Subject: Re: [geda-user] Primitive electrical types [WAS: Re: first attempt at
bus support in gnetlist for pcb]
From: "Britton Kerin (britton DOT kerin AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
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On Sat, Jan 9, 2016 at 3:55 AM, Peter Clifton (petercjclifton AT googlemail DOT co=
m)
[via geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:

>
> On 9 January 2016 at 02:53, Britton Kerin (britton DOT kerin AT gmail DOT com) [via
> geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:
>
>>
>> On Fri, Jan 8, 2016 at 3:38 AM, John Doty <jpd AT noqsi DOT com> wrote:
>>
>>>
>>> Yes. And then, erase the distinction between nets, busses, pins, and
>>> lines. Move that into attributes: a line with netname=3D is a net, a li=
ne
>>> with pinnumber=3D is a pin =E2=80=A6
>>>
>>
>> Using attributes like this is effectively a form of duck typing, which i=
s
>> fine in principle but often leads to a lot of confusion since the type
>> hierarchy is implicit and doesn't end up getting written down anywhere.
>> I'm not saying its always bad and gschem already has this philosophy
>> anyway, but it does tend to make the whole setup challenging for newcome=
rs
>> as they struggle to figure out which sets of attributes they need.
>>
>> I don't have a concrete idea what could be done about it.  It's been an
>> issue for every attribute-based system I've worked on and I've never
>> encountered a great solution.
>>
>
>
> I'm not sure I'd go as far as to say "gschem already has this philosophy
> anyway", since geda does actually treat all these objects as distinct
> types, and their types apply semantic meaning when extracting connectivit=
y.
>
> Did you mean "attributes are used in a similar way already"?
>

Yes, and the details about how to use them are scattered in FAQs and other
places.  Hierarchy is hard to figure out.  John and DJ are the only people
I know who really seem to understand how the slotting and pin sequence
attributes work, I think most people probably just avoid them out of fear.


> Whether or not this is fully factored in the code or not, from the
> graphical entity point of view these are effectively sub-type
> specialisations of the line primitive, as John has suggested. Whilst it
> would be technically possible to take this as a more "duck typed" approac=
h,
> I'd probably not suggest it.
>

Me either, unless I had reason to believe it would somehow not confuse the
bejeebers out of everyone.

Britton

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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><div class=3D"gmail_quo=
te">On Sat, Jan 9, 2016 at 3:55 AM, Peter Clifton (<a href=3D"mailto:peterc=
jclifton AT googlemail DOT com">petercjclifton AT googlemail DOT com</a>) [via <a href=3D=
"mailto:geda-user AT delorie DOT com">geda-user AT delorie DOT com</a>] <span dir=3D"ltr"=
>&lt;<a href=3D"mailto:geda-user AT delorie DOT com" target=3D"_blank">geda-user AT d=
elorie.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=
=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=
=3D"ltr"><br><div class=3D"gmail_extra"><div class=3D"gmail_quote">On 9 Jan=
uary 2016 at 02:53, Britton Kerin (<a href=3D"mailto:britton DOT kerin AT gmail DOT co=
m" target=3D"_blank">britton DOT kerin AT gmail DOT com</a>) [via <a href=3D"mailto:ge=
da-user AT delorie DOT com" target=3D"_blank">geda-user AT delorie DOT com</a>] <span dir=
=3D"ltr">&lt;<a href=3D"mailto:geda-user AT delorie DOT com" target=3D"_blank">ged=
a-user AT delorie DOT com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quot=
e" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204)=
;padding-left:1ex"><div dir=3D"ltr"><br><div class=3D"gmail_extra"><div cla=
ss=3D"gmail_quote"><span>On Fri, Jan 8, 2016 at 3:38 AM, John Doty <span di=
r=3D"ltr">&lt;<a href=3D"mailto:jpd AT noqsi DOT com" target=3D"_blank">jpd AT noqsi.=
com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"mar=
gin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1=
ex"><div style=3D"word-wrap:break-word"><br><div>Yes. And then, erase the d=
istinction between nets, busses, pins, and lines. Move that into attributes=
: a line with netname=3D is a net, a line with pinnumber=3D is a pin =E2=80=
=A6</div></div></blockquote><div><br></div></span><div>Using attributes lik=
e this is effectively a form of duck typing, which is fine in principle but=
 often leads to a lot of confusion since the type hierarchy is implicit and=
 doesn&#39;t end up getting written down anywhere.=C2=A0 I&#39;m not saying=
 its always bad and gschem already has this philosophy anyway, but it does =
tend to make the whole setup challenging for newcomers as they struggle to =
figure out which sets of attributes they need.</div><div><br></div><div>I d=
on&#39;t have a concrete idea what could be done about it.=C2=A0 It&#39;s b=
een an issue for every attribute-based system I&#39;ve worked on and I&#39;=
ve never encountered a great solution. =C2=A0</div></div></div></div></bloc=
kquote><div><br><br></div><div>I&#39;m not sure I&#39;d go as far as to say=
 &quot;gschem already has this philosophy anyway&quot;, since geda does act=
ually treat all these objects as distinct types, and their types apply  sem=
antic meaning when extracting connectivity.<br><br></div><div>Did you mean =
&quot;attributes are used in a similar way already&quot;?<br></div></div></=
div></div></blockquote><div><br></div><div style=3D"">Yes, and the details =
about how to use them are scattered in FAQs and other places.=C2=A0 Hierarc=
hy is hard to figure out.=C2=A0 John and DJ are the only people I know who =
really seem to understand how the slotting and pin sequence attributes work=
, I think most people probably just avoid them out of fear.</div><div>=C2=
=A0</div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;borde=
r-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr"><div class=3D"gmai=
l_extra"><div class=3D"gmail_quote"><div>Whether
 or not this is fully factored in the code or not, from the graphical=20
entity point of view these are effectively sub-type specialisations of=20
the line primitive, as John has suggested. Whilst it would be technically p=
ossible to take this as a more &quot;duck typed&quot; approach, I&#39;d pro=
bably not suggest it.<br></div></div></div></div></blockquote><div><br></di=
v><div style=3D"">Me either, unless I had reason to believe it would someho=
w not confuse the bejeebers out of everyone.</div><div style=3D""><br></div=
><div style=3D"">Britton</div></div><br></div></div>

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